Will Doug's Headers Fit or What???

Will fit no problem! The only time you'll have a problem is if you have a 4 speed, that's it. Also I strongly suggest you use a mini starter, you don't have to but if you ever have to change the starter, you'll wish like hell you used a mini starter.
The neatest difference between Doug's and TTi is that TTi is about 200 bucks more and are a step header going from 1 5/8 to 1 3/4. You won't see any real jump in power useless you motor is pushing a lot of power.